Introduction to Storage technologies

This presentation gives an overview of physical storage technologies and the various ways of accessing storage on a computer or a server. Presented at School of Engineering and Applied Science, Ahmedabad University as a part of Software Engineering course.

1. Introduction to Storage Technologies Kaivalya Shah

2. How is data stored? Data that is accessed, modified, or written by a computer (electronic device) is stored physically using some technology. The technology can be: Magnetic Disk Drive Solid State Drive Optical Disk Drive Magnetic Tape Drive The type of disk used depends on factors like budget, I/O requirement, longevity, and interface compatibility.

3. Magnetic Disk Drive In a magnetic disk drive, data is stored on magnetic plates which are physically accessed using a spindle and a read/write head. Each plate is divided into sectors and tracks. Performance measure: RPM, IOPS

4. Solid State Drive (SSD) A solid state drive is made of non-volatile NAND flash memory which is much faster than magnetic disk drives. There are no mechanically moving parts in an SSD. An SSD controller manages all I/O operations. There are mainly 3 types of SSDs available: Single Level Cell (SLC): 1 bit per flash cell. Highest performance and longevity but very expensive. Enterprise-MLC ( eMLC ): 2 bits per flash cell. Most commonly used due to strong error correction. Triple Level cell (TLC): High density and capacity but low performance and reliability.

5. Direct Attached Storage (DAS) Direct Attached Storage is data storage which is physically connected to a computer using an interface. There are many types of interfaces: USB: Rarely used for servers, common for users. 5 Gbps . SATA (Serial AT Attachment): Used for SSDs. Inexpensive. 16 Gbps . PCIe (Peripheral Component Interconnect Express): High performance but expensive. ~2 GBps . SCSI (Small Computer System Interface): Legacy. Many new standards based on it. Popular protocol which defines a command set. 5 MBps . SAS (Serial Attached SCSI): Replaced SCSI. Popular due to command set. 12 Gbps .

6. Network Attached Storage (NAS) Network Attached Storage is a storage device which is capable of being accessed over a network. The NAS can be connected by a wire (through a server) or wirelessly (USB ports on Wi-Fi routers/access points). It uses file based protocols like SMB (Server Message Block), CIFS (Common Internet File System), and NFS (Network File System). A NAS is generally only accessed like an external drive on a computer because it is a file-level storage. FTP is commonly used with NAS devices. E.g.: \\IETSRV02 (10.20.10.52)

7. Storage Area Network (SAN) A Storage Area Network provides block-level data storage to servers. A SAN acts just like an internal drive to a server. The processing is handled by a storage controller (like a Network Interface Card). It is not necessary for a SAN to use Ethernet. A SAN cannot be accessed directly via a Local Area Network, it uses specific standards like: FCoE (Fiber Channel over Ethernet) FCSAN (Fiber Channel SAN) iSCSI (Internet Small Computer Systems Interface) A SAN also allows for advanced features like multipathing , RAID, and storage virtualization.

8. Thank You